1. Field of the Invention
The present invention relates to a method, system, and program for prioritizing input/output (I/O) requests submitted to a device driver.
2. Description of the Related Art
A host or server system may concurrently execute multiple application programs that generate Input/Output (I/O) requests that are transmitted to a host bus adaptor providing a link to a storage subsystem. The storage subsystem may be comprised of multiple disks, such as the case with a Direct Access Storage Device (DASD), Just a Bunch of Disks (JBOD), a Redundant Array of Independent Disks (RAID), etc. In such subsystems, each application executing in the host may be assigned to use a particular logical volume in the storage subsystem, also referred to as a Logical Unit Number (LUN).
Certain applications executing in a host may be mission critical. For instance, database application programs may require immediate read/write access to storage to ensure that updates are hardened in storage and requested data is received immediately because performance delays could have costly consequences. For instance a large database for a financial institution receiving real-time financial transactions is mission critical in that it is imperative that such real-time financial transactions be immediately applied to storage and that account data be immediately accessible to the application to enable authorized transactions. On the other hand, other applications executing in the host may not be mission critical and the data they generate is of less critical value. For instance, an accounting or engineering department may not need immediate access to data. Further, the loss of data may not result in significant liability and lost data may readily be recovered or reconstructed.
There is a need in the art to provide an improved technique for handling I/O requests for different applications executing within a host that is sensitive to the importance of the I/O requests generated from different applications.